ADSORPTION CHARACTERISTICS OF NITRIC OXIDE ONTO POROUS CARBON-BASED MATERIALS

Adsorption characteristics of nitric oxide (NO) onto porous carbon-based materials, such as coconut shell activated carbon (CSAC), coal activated carbon (CAC) and viscose-based activated carbon fiber (VACF), at 298-343 K were investigated herein. Moreover, influence of pore structure and surface functional groups of adsorbents on NO adsorption behaviors were also studied. According to results of Brunauer-Emmett-Teller (BET) characterization and Boehm titration, it can be inferred that both adsorbent pore structure and surface functional groups could affect NO adsorption behaviors. Adsorption characteristics of NO onto adsorbents prepared from a same precursor were mainly determined by their pore structure. Mesopores as transport pores could play an important role in NO adsorption process like micropores. From results of Boehm titration, it can be found that increasing total acidity contents of adsorbents surface was conducive to improving NO adsorption capacity. NO adsorption capacities of four adsorbents increased rapidly with NO partial pressure at different temperatures. The adsorption equilibrium data for NO adsorbed onto CSAC were fitted to Freundlich, Dubinin-Radush-kevich (D-R) and Sips adsorption isotherm model which was found to be more suitable for description of NO adsorption process at 298 and 313 K; however, D-R adsorption isotherm model was more suitable for description of NO adsorption process at 328 and 343 K. Furthermore, NO adsorption behaviors at a wider temperature range can be predicted from this research. All of these investigations were conducive to analyzing characteristics and mechanism of NO adsorption-oxidation onto a carbon-based supported catalyst in low-temperature denitration technology.